Problem: Which of the following numbers is a factor of 100? ${5,6,8,13,14}$
Explanation: By definition, a factor of a number will divide evenly into that number. We can start by dividing $100$ by each of our answer choices. $100 \div 5 = 20$ $100 \div 6 = 16\text{ R }4$ $100 \div 8 = 12\text{ R }4$ $100 \div 13 = 7\text{ R }9$ $100 \div 14 = 7\text{ R }2$ The only answer choice that divides into $100$ with no remainder is $5$ $ 20$ $5$ $100$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $5$ are contained within the prime factors of $100$ $100 = 2\times2\times5\times5 5 = 5$ Therefore the only factor of $100$ out of our choices is $5$. We can say that $100$ is divisible by $5$.